Process for hydrorefining a hydrocarbon charge stock

ABSTRACT

THIS INVENTION RELATES TO A PROCESS FOR THE HYDROREFINING OF PETROLEUM CRUDE OILS, HEAVY VACUUM GAS OILS, HEAVY CYCLE STOCKS, CRUDE OIL RESIDUUM, TOPPED CRUDE OIL, TAR SAND OIL, SHALE OIL, LIQUIFIED COAL, ETC. MORE SPECIFICALLY THE PRESENT INVENTION INVOLVES A PROCESS FOR HYDROREFINING HEAVY HYDROCARBON CHARGE STOCKS TO EFFECT THE REMOVAL OF NITROGEN AND SULFUR THEREFROM, AND IS ADVANTAGEOUS WHEN EMPLOYED FOR THE DESTRUCTIVE REMOVAL OF ORGANOMETALLIC CONTMINANTS AND PARTICULARLY THE CONVERSION OF PENTANE-INSOLUBLE HYDROCARBONACEOUS MATERIAL.

United States Patent 3,825,488 PROCESS FOR HYDROREFINING A HYDRO- CARBONCHARGE STOCK John G. Gatsis, Des Plaines, Ill., assignor to UniversalOil Products Company, Des Plaines, II]. No Drawing. Filed May 7, 1973,Ser. No. 358,198 Int. Cl. Cg 23/06, 31/14 U.S. Cl. 208-212 6 ClaimsABSTRACT OF THE DISCLOSURE This invention relates to a process for thehydrorefining of petroleum crude oils, heavy vacuum gas oils, heavycycle stocks, crude oil residuum, topped crude oil, tar sand oil, shaleoil, liquefied coal, etc. More specifically the present inventioninvolves a process for hydrorefining heavy hydrocarbon charge stocks toeffect the removal of nitrogen and sulfur therefrom, and is advantageouswhen employed for the destructive removal of organometallic contaminantsand particularly the conversion of pentane-insoluble hydrocarbonaceousmaterial.

Petroleum crude oil, heavier hydrocarbon fractions and/or distillatesobtained therefrom and other hydrocarbons derived from various solidmineral deposits contain nitrogenous and sulfurous compounds in largequantifies. In addition the above-mentioned hydrocarbons generallycontain detrimental quantities of organometallic contaminants whichexert deleterious effects upon the catalyst utilized in variousprocesses to which such hydrocarbons may ultimately be subjected. Themore common of such metallic contaminants are nickel and vanadium, oftenexisting in concentrations in excess of 50 p.p.m. although other metalsincluding copper, iron, etc., may be present. An intensive treatment isrequired to effect the destructive removal of organo-metallic compounds,such as metal porphyrins, particularly to the degree necessary toproduce a crude oil or heavy hydrocarbon fraction which is suitable forfurther processing.

The above-mentioned heavy hydrocarbons contain greater quantities ofsulfurous and nitrogeneous compounds than are generally found in lighterhydrocarbon fractions such as naphtha, kerosene, etc. For example, aWyoming sour crude, having a gravity of 232 API at 60 F., contains about2.8% by weight of sulfur, 8.3 percent by weight pentane-insolubles, 3800p.p.m. of nitrogen and 85 p.p.m. of metallic contaminants. Thenitrogenous and sulfurous compounds are converted, upon being subjectedto a catalytic hydrorefining process, into hydrocarbons, ammonia andhydrogen sulfide; the reduction in the concentration of theorgano-metallic contaminants is not as easily achieved, and to theextent that the same no longer exert a detrimental effect, particularlyin regard to further processing of the hydrocarbon oil. When ahydrocarbon charge stock containing metals in excess of about 3 p.p.m.,is subjected to a fluid catalytic cracking process for the purpose ofproducing lower-boiling components, the metals become deposited upon thecatalyst employed, steadily increasing in quantity until such time asthe composition of the catalyst composite is changed to the extent thatundesirable results are obtained.

However, in addition to the foregoing contaminating influences, crudeoils and other heavier hydrocarbon fractions contain excessivequantities of pentane-insoluble material. For example, the Wyoming sourcrude described above consists of about 8.3% by weight ofpentaneinsoluble asphaltenes. These are hydrocarbonaceous compoundshaving the tendency to become immediately deposited within the reactionzone, and onto the catalyst composite, in the formof an exceedingly highmolecular weight, gummy residue. Since this constitutes a large loss ofcharge stock, it is economically desirable to convert such asphaltenesinto useful hydrocarbon oil fractions, thereby increasing the liquidyield based upon the quantity of oil charged to the process.Furthermore, the deposition of this heavy material onto the catalyticcomposite has the effect of shielding the active centers and surfacesthereof from the material being processed. The conversion of thesepentane-insoluble asphaltenes is that function of the catalyst mostdifficult to achieve, and not withstanding an acceptable degree ofelimination of the other contaminants, the liquid product effluent maycontain a detrimental amount of this material.

When heavy hydrocarbons are produced and collected, many assorted andextraneous contaminants such as metallic oxide and sulfide scale, sand,crushed rock, grit, etc., are often present. Various techniques havebeen employed including filtering, centrifuging and settling to reducethe amount of extraneous contaminants but these separation techniques,when applied to heavy hydrocarbons, are slow, tedious and expensive.Since large volumes of heavy hydrocarbons must be processed inrelatively short periods of time, the cost of the required equipment isprohibitive. The above-mentioned separation techniques are nicely suitedfor carefully controlled laboratory experiments or for the production ofrefined chemicals but not for the initial hydrorefining of heavyhydrocarbons.

The public as well as the hydrocarbon producing companies have recentlybecome acutely aware of a potential energy crises. The increasing costof producing conventional oil reserves and the depletion of the easilyavailable sources of oil have made the recovery of hydrocarbons from tarsand and shale much more attractive.

Large deposits of bituminous sands are found in various localitiesthroughout the world. The term bituminous sand is used herein to includethose materials commonly referred to as oil sands, tar sands, and thelike. One of the most extensive deposits of bituminous sands occurs forinstance in the Athabasca district of the Province of Alberta, Canada,and extends for many thousands of square miles in thickness ranging inup to more than two hundred feet.

Since the crude oil obtained from this type of bituminous sand isrelatively viscous material having high tar content and relatively lowcommercial value in comparison with other crude oils, a successfulcommercial process must involve relatively little expense in theseparation of the crude oil from the bituminous sands. Operating costsof previously conceived methods for separating the oil have beensufficiently high so as to discourage commercial exploitation.

In attempting to separate crude oil from bituminous sands, considerabledifficulty has been experienced due to the fact that the solids contentof bituminous sands consists of particles of varying size and includessubtantial amounts of silt in the form of clay and other very fine solidparticles. In attempting to effect a complete separation of the crudeoil from the bituminous sands previous processes have attempted toretain the silt with the remainder of the solids content of the sandsand as a result have usually discarded considerable quantities of crudeoil along with such slit and sand. Entrapped particles ranging in sizefrom 1 to about microns appear to be the most difficult to remove.

Therefore, it is highly desirable that an initial hydrorefining processbe capable of processing heavy hydrocarbons which contain finely dividedparticles of sand, silt, metallic sulfide and oxide scale, etc.

An object of the present invention is to provide a more efficientprocess for hydrorefining heavy hydrocarbonaceous material, andparticularly tar sand oil and shale oil, utilizing an unsupportedcatalyst. The term hydrorefining as employed herein, connotes thecatalytic treatment, in an atmosphere, of hydrogen of a petroleum crudeoil, or a hydrocarbon fraction or distillate for the purpose ofeliminating and/ or reducing the concentration of the variouscontaminating influences previously described. As hereinabove set forth,metals are generally removed from the charge stock by deposition of thesame on the catalyst employed. This increases the amount of catalyst,actively shields the catalytically active surfaces and centers from thematerial being processed, and thereby virtually precludes theutilization of a fixed-bed catalyst systemfor processing suchcontaminated crude oil. Various moving-bed processes, employingcatalytically active metals deposited upon a carrier materialconsisting, for example, of silica and/ or alumina, or other refractoryinorganic oxide materials, are extremely erosive, causing plantmaintenance to become diflicult and expensive. The present inventionteaches the preparation of a colloidally dispersed, unsupportedcatalytic material useful in a slurry process, which catalytic materialwill not effect extensive erosion or corrosion of the reaction system.The present process yields a liquid hydrocarbon product which is moresuitable for further processing without experiencing the diflicultiesotherwise resulting from the presence of the foregoing contaminants. Theprocess of the present invention is particularly advantageous foreffecting the conversion of sulfurous, nitrogenous and theorgano-metallic contaminants without significant product yield loss,while simultaneously converting a substantial quantity of pentane-insoluble material into pentane-soluble liquid hydrocarbons.

It is another object of the present invention to provide an improvedprocess for the production of distillable hydrocarbons from heavyhydrocarbonaceous material which contains finely divided particles ofsand, silt, metallic sulfide and oxide scale, etc.

It is a further object of the invention to provide for a suitable andeconomical fuel to supply the heat and power requirements of theproduction facility or any other facility.

In a broad embodiment, the present invention relates to a process forhydrorefining a hydrocarbon charge stock which comprises: a process forhydrorefining a hydrocarbon charge stock which comprises the steps of:(a) reacting said charge stock with hydrogen at hydrorefining conditionsutilizing a catalyst comprising a heteropoly acid containing a Group V-Bmetal component or a Group VI-B metal component having an atomic numbergreater than 24; (b) separating the hydrorefining reaction efiiuent torecover a distillable hydrocarbon fraction and a nondistillable fractionwhich contains said metal component; oxidizing said non-distillablefraction to provide energy and to produce an oxide of said metalcomponent; (d) contacting the resulting metal oxide with a liquidsolution of an acid selected from phosphoric acid and silicic acid toproduce a liquid solution of a heteropoly acid containing said metalcomponent; and, (e) passing said heteropoly acid to reaction Step (a).

A more limited embodiment of the present invention involves a processfor hydrorefining a hydrocarbon charge stock which comprises combiningsaid charge stock with phosphomolybdic acid, heating the resultingmixture at a temperature less than about 310 C. and for a timesufficient to produce a colloidal dispersion of said phosphomolybdicacid, reacting said colloidal dispersion with hydrogen at a temperaturewithin the range of from about 225 C. to about 500 C. and at a pressureof about 500 to about 5000 p.s.i.g., separating the hydrorefiningreaction efiiuent to recover a distillable hydrocarbon fraction and anon-distillable fraction which contains said phosphomolybdic acid,oxidizing said non-distillable fraction to provide energy for theproduction facility or any other facility and to produce molybdenumoxide, treating the resulting molybdenum oxide with phosphoric acid toform said phosphomolybdic acid and recycling the newly formedphosphomolybdic acid.

From the foregoing embodiments, it is noted that the method of thepresent invention involves the preparation of a catalyst utilizingmetals selected from Group V-B and Group VI-B of the Periodic Table.Reference is herein made to the Periodic Chart of the Elements, pages448 and 449, 43rd edition of Handbook of Chemistry and Physics. It isfurther noted that the metals for Group VI B namely molybdenum and/ortungsten, have an atomic number greater than 24. It has been found thatheteropoly acids of chromium, in addition to other chromium complexes,upon decomposition within the hydrocarbon charge stock, do not yieldacceptable economical results and particularly with respect to theconversion of the pentaneinsoluble fraction and the organo-metalliccompounds such as the nickel and/or vanadium porphyrins. Furthermore,the decomposition of such chromium complexes is effected above about 310C., resulting in premature thermal cracking of the crude oil. Briefly,the catalyst is preferably prepared by dissolving heteropoly acids ofmolybdenum, tungsten or vanadium, such as phosphomolybdic acid,silicomolybdic acid, phosphotungstic acid, silicotungstic acid,phosphovanadic acid and silicovanadic acid in an appropriate solventsuch as alcohols containing up to and including about ten carbon atomsper molecule. Although alcohols are the preferred solvents, additionalsolvents may be used such as water, acetone, ethyl acetate, etc. Thesolution is added to the petroleum crude oil and the mixture distilledwith stirring, at a temperature less than about 310 C., to remove thesolvent and form a col loidally dispersed catalyst suspended within thepetroleum crude oil. The quantity of the heteropoly acid employed issuch that the colloidal suspension, or dispersion, which results uponremoval of the solvent, comprises from about 1.0% to about 10.0% byweight, calculated, however, as the elemental metal. The heteropolyacids may be used in combination of two or more of the acids describedabove.

When the heteropoly acid is initially dissolved in an alcohol containingup to and including about ten carbon atoms per molecule, thecontaminating influences, with the exception of asphaltenes, containedwithin the petroleum crude oil are removed to the extent that the futureprocessing of such crude oil no longer incurs the detrimental effectsotherwise resulting from the presence of these contaminating influences.As previously set forth, the conversion of asphaltenes is most diflicultto achieve; further, as the concentrations of the other contaminantsincreases, the degree of conversion of the asphaltenes is lessened.Typical of the alcohols suitable for use in preparing the solution ofthe desired heteropoly metallic acid 1nclude isopropyl alcohol,isopentyl alcohol, methyl alcohol, amyl alcohol, mixtures thereof, etc.The mixture of the alcohol solution of the heteropoly acid and thepetroleum crude oil is heated at a temperature below about 310 C. forthe purpose of distilling the alcohol, leaving the heteropoly acid as acolloidal dispersion within the crude oil. Temperatures above about 310C. tend to result in premature cracking reactions whereby theeffectiveness to convert pentane-insoluble asphaltenes becomes adverselyaffected.

The colloidal dispersion is then passed into a suitable reaction zonemaintained at a temperature within the range of from about 225 C. toabout 500 C. and under a hydrgen pressure within the range of about 500to about 5000 p.s.i.g. The process may be conducted in a batchtypeprocedure or in an enclosed vessel through which the colloidalsuspension is passed; when effected in a continuous manner, the processmay be conducted in either upward flow or downward flow.

As hereinabove set forth, the hydrorefining catalyst utilized in theprocess of the present invention, exists as a colloidal dispersionwithin the hydrocarbonaceous charge stock being subjected to reactionwith hydrogen. Thus the catalyst is a colloidally dispersed heteropolyacid selected from the group which has been previously described.

The following example is presented as a further illustration of theprocess of this invention and the advantages to be derived therefromwith respect to the conversion of pentane-insoluble asphaltenes, removalof metallic contaminants, the conversion of nitrogenous and sulfurouscompounds to nitrogen-free and sulfur-free hydrocarbons and thesatisfactory disposal of indigenous particulate matter. It is notintended that said example be construed as a limitation on the generallybroad scope of this invention.

The petroleum hydrocarbon charge stock employed to illustrate theprocess of this invention and the particular advantages derivedtherefrom, is a Wyomin sour crude with a gravity of 23.2 API at 60 F., aboiling point of 641 F. and a 50% boiling point of 934 F. The crude oilcontains 8.3 weight percent pentane-insoluble asphaltenes, 2.8 weightpercent sulfur as sulfurous compounds, 27 ppm. of nickel, 71 ppm. ofvanadium and 2.5 weight percent of indigenous particulate matter. Boththe nickel and vanadium are present as metal porphyrins, calculated asthe elemental metal. As hereinafter illustrated, the process of thisinvention effects the conversion of a substantial portion of saidasphaltenes and the disposal of said indigenous particulate matter whilesubstantially simultaneously effecting the conversion of the metalliccontaminants and nitrogenous and sulfurous compounds to the extent thatthe same no longer exert an adverse etfect on subsequent processingprocedures.

EXAMPLE A colloidal dispersion of phosphomolybdic acid is prepared byinitially dissolving 30 grams of the phosphomolybdic acid in 400 gramsof isopropyl alcohol. One thousand grams of the crude, as hereinbeforedescribed, is placed in a two-liter reaction flask containing a stirrer,and the isopropyl alcohol solution is added thereto in drop-wisefashion. The temperature of the contents of the two-liter flask ismaintained at 130 C. such that the alcohol is distilled while thesolution is added to the crude.

An 1800 milliliter, rocker-type autoclave is selected and 200 grams ofthe colloidal dispersion is placed therein. The autoclave is pressuredto 1500 p.s.i.g. with hydrogen and is heated to a temperature of 390 C.After five hours at these conditions, the contents of the autoclave iscooled to room temperature, removed therefrom and subjected tofractionation thereby recovering a distillable fraction and anon-distillable fraction. Said distillable fraction is free from metals,asphaltenes and particulate matter and contains substantially reducedquantities of sulfur and nitrogen which fraction is then suitable forfurther processing in conventional refining processes. Saidnon-distillable fraction which contains said phosphomolybdic acid andreduced quantities of asphaltenes and organo-metallic compounds isoxidized to supply energy and to produce molybdenum oxide. Themolybendum oxide is recovered and treated with phosphoric acid solutionto form phosphomolybdic acid which is then used again in the earlystages of the process.

I claim as my invention:

1. A process for hydrorefining a hydrocarbon charge stock whichcomprises the steps of:

(a) reacting said charge stock with hydrogen at hydrorefining conditionsutilizing a catalyst comprising a heteropoly acid containing a Group V-Bmetal component or a Group VI-B metal component having an atomic numbergreater than 24;

(b) separating the hydrorefining reaction efiiuent to recover adistillable hydrocarbon fraction and a nondistillable fraction whichcontains said metal component;

(c) oxidizing said non-distillable fraction to provide energy and toproduce an oxide of said metal components;

(d) contacting the resulting metal oxide with a liquid solution of anacid selected from phosphoric acid and silicic acid to produce a liquidsolution of a heteropoly acid containing said metal component; and,

(e) passing said heteropoly acid to reaction Step (at).

2. The process of claim 1 further characterized in that said heteropolyacid is commingled with said hydrocarbon charge stock and the resultingmixture is heated at a temperature less than 310 F. for a timesuflicient to form a colloidal dispersion of said heteropoly acid priorto reacting said charge stock with said hydrogen.

3. The process of claim 1 further characterized in that said metalliccomponent is selected from molybdenum, tungsten and vanadium.

4. The process of claim 1 further characterized in that said heteropolyacids are selected from phosphomolybdic acid, silicomolybdic acid,phosphotungstic acid, silicotungstic acid, phosphovanadic acid andsilcovanadic acid.

5. The process of claim 1 further characterized in that said hydrocarboncharge stock is reacting with hydrogen at a temperature within the rangeof about 225 C. to about 500 C. and under a pressure of from about 500p.s.i.g. to about 5000 p.s.i.g.

6. The process of claim 1 further characterized in that said hydrocarboncharge stock is selected from tar sand oil and shale oil.

References Cited UNITED STATES PATENTS 3,432,442 3/ 1969 Gleim 208-2533,232,887 2/1966 Pessimisis 252-435 3,617,528 11/1971 Hilfman 208-2163,755,150 8/ 1973 Mickelson 2082l6 CURTIS R. DAVIS, Primary Examiner US.Cl. X.R.

